Gating-induced large aqueous volumetric remodeling and aspartate tolerance in the voltage sensor domain of Shaker K+ channels

Indexación: Scopus.ACKNOWLEDGMENTS. We thank Chris Lingle and Yu Zhou (Washington University) for critical reading of the manuscript and Victoria Prado for Xenopus care and oocyte preparation. We also thank Millennium Scientific Initiative P029-022-F. This work was supported by Fondecyt Postdoctoral Grants 3170599 (to I.D.-F.) and 3160321 (to H.M.).Neurons encode electrical signals with critically tuned voltage-gated ion channels and enzymes. Dedicated voltage sensor domains (VSDs) in these membrane proteins activate coordinately with an unresolved structural change. Such change conveys the transmembrane translocation of four positively charged arginine side chains, the voltage-sensing residues (VSRs; R1–R4). Countercharges and lipid phosphohead groups likely stabilize these VSRs within the low-dielectric core of the protein. However, the role of hydration, a sign-independent charge stabilizer, remains unclear. We replaced all VSRs and their neighboring residues with negatively charged aspartates in a voltage-gated potassium channel. The ensuing mild functional effects indicate that hydration is also important in VSR stabilization. The voltage dependency of the VSR aspartate variants approached the expected arithmetic summation of charges at VSR positions, as if negative and positive side chains faced similar pathways. In contrast, aspartates introduced between R2 and R3 did not affect voltage dependence as if the side chains moved outside the electric field or together with it, undergoing a large displacement and volumetric remodeling. Accordingly, VSR performed osmotic work at both internal and external aqueous interfaces. Individual VSR contributions to volumetric works approached arithmetical additivity but were largely dissimilar. While R1 and R4 displaced small volumes, R2 and R3 volumetric works were massive and vectorially opposed, favoring large aqueous remodeling during VSD activation. These diverse volumetric works are, at least for R2 and R3, not compatible with VSR translocation across a unique stationary charge transfer center. Instead, VSRs may follow separated pathways across a fluctuating low-dielectric septum. © National Academy of Sciences. All rights reserved.https://www.pnas.org/content/115/32/820

Genomic organization of nucleolin gene in carp fish: Evidence for several genes

http://www.scielo.cl/scielo.php?script=sci_arttext&pid=S0716-97602006000200017&lng=es&nrm=isoThe protein nucleolin, functionally involved in the main steps of ribosome biogenesis, is codified by a single copy gene in mammals. Here we report that at least three different genes codify for this protein in carp fish (Cyprinus carpio). This is the first description of the genomic organization of nucleolin in a teleost. The carp nucleolin gene includes 8.8 kb and contains 16 exons. Promoter cis regulatory elements are similar to constitutive genes, i.e., a putative TATA box, three G/C boxes, and three pyrimidine-rich boxes. As in other species, carp nucleolin gene introns host three snoRNA codifying sequences: U23 from the H/ACA family and two C/D box snoRNAs, U20 and U82. Both U20 and U82 span a complementary sequence with carp 18S rRNA. Additionally, we identified two cDNAs coding for nucleolin, confirming the existence of several nucleolin genes in carp. Amino acidderived sequence from carp cDNAs differ from mammal protein because they span additional acidic domains at the amino end, whose functional significance remains unclear. We performed amino acid sequence comparison and phylogenetic analyses showing that the three isoforms of carp nucleolin, which we describe herein, cluster in two groups. cNUC1 probably diverges from cNUC2 and cNUC3 as result of ancestral fish-specific genome duplication, indeed C. carpio is a tetraploid fish

Nivel de conocimientos sobre manejo de las claves obstétricas en internos de ciencias de la salud y la reacción frente a las emergencias obstétricas en el Hospital de la Amistad Perú Corea Santa Rosa – Piura 2018

En el mundo, invertir en estrategias que disminuyan la muerte materna es prioridad a fin de mejorar las condiciones de vida de la población, asimismo no existe evidencia real de mortalidad materna, ya que en muchas zonas alejadas se suceden muertes sin que estas sean conocidas por los profesionales que cuidan la salud, también por aquellos nacimientos que se dan en zonas rurales donde no se capacita constantemente al personal de salud, en ese sentido y con la finalidad de determinar la relación que existe entre el nivel de conocimiento y la reacción de los internos frente a las emergencias obstétricas en internos de ciencias de la salud del Hospital Santa Rosa de Piura, se realizó una investigación correlacional no experimental trasversal, donde se contó con una muestra de 66 internos de las profesiones de Medicina y Obstetricia, se empleó como técnica de recolección de datos la encuesta y como instrumento un cuestionario elaborado por el investigador aprobado por juicios de expertos, teniendo como resultados: que el coeficiente Rho de Spearman entre las Variables conocimiento claves y reacción a emergencias en 60 internos fue de 0,252, valor que señala una correlación baja y positiva (directa), el valor de “p valor” = 0,052, esto determino que no existe relación considerable entre el conocimiento acerca de las claves obstétricas y la reacción ante las emergencias obstétricas de los internos de ciencias de la salud del Hospital Santa Rosa. Finalmente se puede concluir manifestando que a pesar de tener una buena reacción frente a las emergencias obstétricas el conocimiento sigue estando en niveles medios a bajos

Molecular evolution of tropinone-reductase-like and tau GST genes duplicated in tandem in Brassicaceae

Gene duplication is an opportunity for evolving new functions from the newer gene, but also has a disadvantage due to local gene-rearrangement effects and, if duplications are numerous, through alterations of genome size. Therefore, selection is playing a central role in determining the fate of a duplicate gene. Plants are known to harbor numerous gene families, and are thus an ideal system to test the fate of gene duplicates. This thesis tackles the tropinone-reductase like enzymes (further TRL) and the tau GSTs located upstream from this gene family. TRL enzymes are short-chain dehydrogenases that are involved in a reduction step downstream in the synthesis of tropane alkaloids in Solanaceae, important defense compounds of plants. The function of TRLs in Brassicaceae is not clear, since most of the plants in this family do not produce tropane alkaloids, but some have been associated with the oxidative-stress response. This gene family contains 80\% of its members duplicated in tandem in Arabidopsis thaliana. We profited from this fact to isolate 12 TRL (+ pseudogenes) from this species, further six species of Brassicaceae (A. thaliana, A. lyrata, A. cebennensis, Capsella rubella, Boechera divaricarpa and Brassica rapa), and one species from a closely related plant family, Cleome spinosa. We tested the role that selection plays in maintaining large numbers of this gene family. We used phylogenetic methods to analyze non-coding sequence evolution and identified regulatory motifs. We analyzed non-coding sequence evolution. Microarray expression data from A. thaliana and qPCR for A. thaliana and A. lyrata were analyzed to detect divergence in the expression patterns of orthologs and paralogs. TRL genes follow a gene birth and death dynamics. More probable, they originated from non-equal recombination of tandem duplicated genes. Positive selection at the origin of the duplicated genes allowed these to acquire differential expression patterns, leading to the preservation of numerous TRLs. The analysis of coding and non-coding sequences shows them to display correlated evolution, particularly in species recently separated by speciation. We further tested for selection on the tau glutathione-S-transferases (GST) enzymes, adjacent 3' in the genome to TRLs. Tau GSTs are unique to plants and are involved in detoxification. Multiple copies of these enzymes will allow flexibility in substrate specificity, which is important for the detoxification function. We detected positive selection among paralogs of tau GSTs supporting their potential of functional diversity, but we also detected negative selection among paralogs and groups of orthologs, indicating that more often their functions are conserved

Between schools and bullets: an approach to Mass Shooting

El presente artículo es una recopilación histórica y teórica de algunos estudios que han analizado el fenómeno de los tiroteos masivos en las escuelas desde la psicología, psiquiatría, criminología y pedagogía. Lo anterior permite a los autores hacer una indagación académica de estos fenómenos que afectan los climas escolares y ponen en evidencia la grave problemática que implican los casos de tiroteos al interior de las instituciones educativas. El abordaje de este material bibliográfico conduce al lector a conocer una aproximación al fenómeno de las masacres en instituciones educativas, pasando de un estado de violencia escolar a criminalidad escolar a una breve presentación de la historia cronológica de los tiroteos masivos en los últimos años de la historia moderna del planeta y la variante de las aristas sociales que se mueven alrededor de un crimen ejecutado por un estudiant

Element specific characterization of heterogeneous magnetism in (Ga,Fe)N films

We employ x-ray spectroscopy to characterize the distribution and magnetism of particular alloy constituents in (Ga,Fe)N films grown by metal organic vapor phase epitaxy. Furthermore, photoelectron microscopy gives direct evidence for the aggregation of Fe ions, leading to the formation of Fe-rich nanoregions adjacent to the samples surface. A sizable x-ray magnetic circular dichroism (XMCD) signal at the Fe L-edges in remanence and at moderate magnetic fields at 300 K links the high temperature ferromagnetism with the Fe(3d) states. The XMCD response at the N K-edge highlights that the N(2p) states carry considerable spin polarization. We conclude that FeN{\delta} nanocrystals, with \delta > 0.25, stabilize the ferromagnetic response of the films.Comment: 4 pages, 3 figures, 1 tabl